The interaction between elasticity and capillarity is used to produce three-dimensional structures through the wrapping of a liquid droplet by a planar sheet. The final encapsulated 3D shape is controlled by tailoring the initial geometry of the flat membrane. Balancing interfacial energy with elastic bending energy provides a critical length scale below which encapsulation cannot occur, which is verified experimentally. This length is found to depend on the thickness as $h^{3/2}$, a scaling favorable to miniaturization which suggests a new way of mass production of 3D micro- or nanoscale objects.

A new scheme for the retrieval of total columnar water vapour from measurements of MERIS (Medium Resolution Imaging Spectrometer) on ENVISAT (ENVIronmental SATellite) is presented. The algorithm is based on a fast forward model of the water vapour transmittance around 900nm, including a correction for atmospheric scattering and the influence of the temperature- and pressure-profile on the water vapour absorption lines. It provides the water vapour column amount for cloud-free scenes above land and ocean at a spatial resolution of 0.25 km × 0.3 km and 1 km × 1.2 km, depending on whether applied to the "full resolution" or the operational "reduced resolution" mode of MERIS. Uncertainties are provided on a pixel-by-pixel basis, taking into account all relevant sources of error. An extensive validation against various sources of ground-based reference data reveals a high accuracy of MERIS water vapour above land (root mean square deviations between 1.4 mm and 3.7 mm), apart from a wet bias of MERIS between 5 and 10% that is found in all comparison studies. This wet bias might be caused by spectroscopic uncertainties, such as the description of the water vapour continuum. Above ocean the accuracy is reduced, due to the uncertainty introduced by the unknown atmospheric scattering. Consequently, an increased root mean square deviation of ≥5 mm was found by comparing MERIS total columnar water vapour above ocean against SSM/I and ENVISAT MWR data. An increased wet bias of 2–3 mm is found over ocean, potentially due to a not properly working atmospheric correction scheme.

This study introduces an Earth observation (EO)-based system which is capable of operationally estimating and continuously monitoring the ultraviolet index (UVI) in Europe. UVIOS (i.e., UV-Index Operating System) exploits a synergy of radiative transfer models with high-performance computing and EO data from satellites (Meteosat Second Generation and Meteorological Operational Satellite-B) and retrieval processes (Tropospheric Emission Monitoring Internet Service, Copernicus Atmosphere Monitoring Service and the Global Land Service). It provides a near-real-time nowcasting and short-term forecasting service for UV radiation over Europe. The main atmospheric inputs for the UVI simulations include ozone, clouds and aerosols, while the impacts of ground elevation and surface albedo are also taken into account. The UVIOS output is the UVI at high spatial and temporal resolution (5 km and 15 min, respectively) for Europe (i.e., 1.5 million pixels) in real time. The UVI is empirically related to biologically important UV dose rates, and the reliability of this EO-based solution was verified against ground-based measurements from 17 stations across Europe. Stations are equipped with spectral, broadband or multi-filter instruments and cover a range of topographic and atmospheric conditions. A period of over 1 year of forecasted 15 min retrievals under all-sky conditions was compared with the ground-based measurements. UVIOS forecasts were within ±0.5 of the measured UVI for at least 70 % of the data compared at all stations. For clear-sky conditions the agreement was better than 0.5 UVI for 80 % of the data. A sensitivity analysis of EO inputs and UVIOS outputs was performed in order to quantify the level of uncertainty in the derived products and to identify the covariance between the accuracy of the output and the spatial and temporal resolution and the quality of the inputs. Overall, UVIOS slightly overestimated the UVI due to observational uncertainties in inputs of cloud and aerosol. This service will hopefully contribute to EO capabilities and will assist the provision of operational early warning systems that will help raise awareness among European Union citizens of the health implications of high UVI doses.

In this study we present airborne observations of aerosol and trace gases obtained over the sea in the western Mediterranean basin during the TRAQA (TRansport and Air QuAlity) and SAFMED (Secondary Aerosol Formation in the MEDiterranean) campaigns in summer 2012 and 2013. A total of 23 vertical profiles were measured up to 5000 m above sea level over an extended area (40–45° N and 2° W–12° E) including the Gulf of Genoa, southern France, the Gulf of Lion, and the Spanish coast. During TRAQA and SAFMED the study area experienced a wide range of meteorological conditions which favoured pollution export from different sources located around the basin. Also, several events of dust outflows were measured during the campaigns. Observations from the present study show that continental pollution largely affects the western Mediterranean both close to coastal regions and in the open sea as far as ~ 250 km from the coastline. The measured aerosol scattering coefficient varies between ~ 20 and 120 Mm−1, while carbon monoxide (CO) and ozone (O3) mixing ratios are in the range of 60–165 and 30–85 ppbv, respectively. Pollution reaches 3000–4000 m in altitude and presents a very complex and highly stratified structure characterized by fresh and aged layers both in the boundary layer and in the free troposphere. Within pollution plumes the measured particle concentration in the Aitken (0.004–0.1 μm) and accumulation (0.1–1.0 μm) modes is between ~ 30 and 5000–6000 scm−3 (standard cm−3), which is comparable to the aerosol concentration measured in continental areas under pollution conditions. Additionally, our measurements indicate the presence of highly concentrated Aitken layers (10 000–15 000 scm−3) observed both close to the surface and in the free troposphere, possibly linked to the influence of new particle formation (NPF) episodes over the basin.

Pollution aerosols strongly influence the composition of the Western Mediterranean basin, but at present little is known on their optical properties. We report in this study in situ observations of the single scattering albedo (ω) of pollution aerosol plumes measured over the Western Mediterranean basin during the TRAQA (TRansport and Air QuAlity) airborne campaign in summer 2012. Cases of pollution export from different source regions around the basin and at different altitudes between ∼ 160 and 3500 m above sea level were sampled during the flights. Data from this study show a large variability of ω, with values between 0.84–0.98 at 370 nm and 0.70–0.99 at 950 nm. The single scattering albedo generally decreases with the wavelength, with some exception associated to the mixing of pollution with sea spray or dust particles over the sea surface. The lowest values of ω (0.84–0.70 between 370 and 950 nm) are measured in correspondence of a fresh plume possibly linked to ship emissions over the basin. The range of variability of ω observed in this study seems to be independent of the source region around the basin, as well as of the altitude and aging time of the plumes. The observed variability of ω reflects in a large variability for the complex refractive index of pollution aerosols, which is estimated to span in the large range 1.41–1.77 and 0.002–0.097 for the real and the imaginary parts, respectively, between 370 and 950 nm. Radiative calculations in clear-sky conditions were performed with the GAME radiative transfer model to test the sensitivity of the aerosol shortwave Direct Radiative Effect (DRE) to the variability of ω as observed in this study. Results from the calculations suggest up to a 50 and 30 % change of the forcing efficiency (FE), i.e. the DRE per unit of optical depth, at the surface (−160/−235 W m⁻² τ⁻¹ at 60° solar zenith angle) and at the Top-Of-Atmosphere (−137/−92 W m⁻² τ⁻¹) for ω varying between its maximum and minimum value. This induces a change of up to an order of magnitude (+23/+143 W m⁻² τ⁻¹) for the radiative effect within the atmosphere.